Cast beams for filterbed with cross flow at ends

Abstract

Pre-cast concrete beams for supporting a filterbed have deep downwardly extending flanges for providing an underchannel lengthwise of the beam. The beams generally extend across a flume. For backwashing with an air-water mixture, air should be supplied at substantially the same rate to all of the channels. Cross passages between the channels are an aid to this even distribution. Heretofore, special molding procedures for providing the passages or limbers through the beam flanges have increased manufacturing costs. According to the present invention, such passages are provided without extra molding steps and without extra cost by following a delightfully simple concept of merely omitting the end portions of the flanges where beam strength is not required. The end portion projecting beyond the flanges may have a leg across its end to ensure support and aid sealing.

I claim: 
     
       1. A precast elongate underchanneled floor beam of the class suitable for spanning across a filter-tank floor with an open sluiceway therein across which a number of such beams are laid, in side-by-side relationship, to form a floor for supporting a bed of particulate filter media, said beam including: a floor panel having therethrough apertures for receiving distribution nozzles and apertures for receiving tie down rods; and   flanges formed as part of the same casting and extending downwardly from the floor panel to provide an underchannel extending lengthwise of the beam; said flanges being continuous along the intermediate portions of the length of the beam but being substantially totally omitted near the ends of the beam to provide a crossflow passage from said underchannel to the underchannel of an adjacent similar beam.   
     
     
       2. A precast elongate underchanneled floor beam of the class suitable for spanning across a filter-tank floor with an open sluiceway therein across which a number of such beams are laid, in side-by-side relationship, to form a floor for supporting a bed of particulate filter media, said beam including: a floor panel having therethrough apertures for receiving distribution nozzles and apertures for receiving tie down rods; and   flanges formed as part of the same casting and extending downwardly from the floor panel to provide an underchannel extending lengthwise of the beam; said flanges being continuous along the intermediate portions of the length of the beam but being substantially totally omitted near the ends of the beam to provide a crossflow passage from said underchannel to the underchannel of an adjacent similar beam; said floor panel, at each end beyond the flanges, being provided with a downwardly extending transverse flange, formed as part of the same casting, for aiding support and seal.     
     
     
       3. The method of making a mold-formed elongate underchanneled beam suitable for resting across a sluiceway in a filter-tank floor and being anchored to said floor on opposite sides of the sluiceway, and suitable for supporting a filterbed of particulate media, which includes filling a mold cavity which provides a shallow space for a floor panel; the mold having projections through said shallow space to form passages in said panel, some for receiving nozzles and some for receiving tie down rods; the cavity also having deep spaces extending longitudinally of said shallow space generally at right angles to the plane of the shallow space and opening to it for forming flanges on the floor panel to provide between them an underchannel, said spaces for the flanges extending substantially continuously along both longitudinal edges of the shallow space except being terminated near the ends of the shallow space by mold portions which extend approximately to the shallow space from the plane of the opposing edges of the flange-forming deep spaces to leave a corresponding passage for communication between the said channel and the channel of an adjacent similar beam after installation, said mold portions being so shaped as not to interfere with removal of the molded and hardened beam from the mold and not to require said mold portions to be separare pieces. 
     
     
       4. The method according to claim 3 in which the mold is filled by flowing the molding material into the cavity by gravity to form the beam by casting. 
     
     
       5. A mold-formed elongate underchanneled floor beam, for supporting a filterbed of particulate material and of the class suitable for spanning across a sluiceway in a filter-tank floor, said beam including: a floor panel having therethrough apertures for receiving distribution nozzles and apertures for receiving tie down rods, and   flanges as part of the same molding and extending downwardly from the floor panel to provide an underchannel extending lengthwise of the beam; said flanges being substantially continuous along the intermediate portions of the length of the beam but being substantially totally omitted near the ends of the beam to provide a crossflow passage from said underchannel to the underchannel of an adjacent similar beam.